Adjustable hard ceramic underflow outlet for hydrocyclone

ABSTRACT

A hydrocyclone underflow outlet of hard ceramic material which is relatively strong under compression but weak under tension can be made adjustable in length by a series of grooves formed in its exterior surface permitting the member to be broken off to desired length by hammering a breaking tool wedged in the appropriate groove so that the tension at the base of the groove produced by pressure of the tool sides on the groove sides pulls the material apart at the base of the groove. The body may be frustoconical so that adjustment in length changes the size of an end opening in the body.

I United States Patent [151 3,642,132 Flaherty Feb. 15, 1972 [54]ADJUSTABLE HARD CERAMIC 1,545,295 7/1925 Wilford ..138/160 X UNDERFLOWOUTLET FOR HYDROCYCLONE FOREIGN PATENTS OR APPLICATIONS 769,906 3 1957 GtB 't" ..21 [72] Inventor: Robert Brendan Flaherty, Foxboro, Mass. 812891 51959 ig; n [73] Assignee: Bird Machine Company, South Walpole,10,085 1898 Great Britain ..285/4 Mass 129,288 8/1950 Sweden..'..,239/589 [22] Filed: Apr. 6,1970 OTHER PUBLICATIONS I2] I AppL25,846 Leaflet No. 2505 The P50 Dorrclorie, Llorr-Oliver. lnc.,Stamford, Conn., 1956.

Primary Examiner-Frank W. Lutter I521 U.S. Cl ..209/211 AssistantExaminer Ra1phJ m I51 Int. Cl. ..B04c 5/14 Atmmey Edgar H Kent [58]Field ofSearch ..138/178, 106,107, 103; 285/4;

137/801; 222/566; 239/589; 209/21 1; 210/512 57 S CT [56] ReferencesCited A hydrocyclone underflow outlet of hard ceramic material which rsrelatively strong under compression but weak under UNITED STATES PATENTStension can be made adjustable in length by a series of grooves formedin its exterior surface permitting the member to be gantonr...i..222/566 broken off to desired length by hammering a breaking too] 897at a "209/211 wedged in the appropriate groove so that the tension atthe I 285/4 X base of the groove produced by pressure of the tool sideson 2449754 9/1948 seltz "285/4 the groove sides pulls the material apartat the base of the 1,593,016 7/1926 Carryshell X groove. The y y befrustoconical so h adjustment i length changes the size of an endopening in the body.

1 Claims, 2 Drawing Figures PATENTED FEB I 5 I972 FIG. 2

FIG.

ADJUSTABLE HARD CERAMIC UNDERFLOW OUTLET FOR HYDROCYCLONE This inventionrelates to tubular bodies formed of hard ceramic material useful inequipment for treating abrasive materials such as cyclone separators(which term as herein used includes hydrocyclones).

Because of their great wear resistance, hard ceramic materials arefinding increasing usage for forming the walls of tubular bodies inwhich abrasive materials are treated. For example, cyclone separatorswherein abrasive particles are segregated by centrifugal force againstthe tubular wall thereof frequently have such wall formed of hardceramic material, at least adjacent the outlet end where abrasive wearis greatest.

In many cases it is necessary to reduce the length of such a body assupplied by the manufacturer to the installation site and this presentsa problem in that the ceramic materials used for the purpose, such asceramic materials of high alumina content, are so hard (their hardnessbeing of the order of 75 to 81 as measured on a Rockwell 45N scale whichis approximately equal to 1,000 to 1,100 on a Vickers hardness scale)that a diamond wheel is required to cut them. Since such equipment isnot usually available at installation sites, the body must either bereturned to the manufacturer or sent elsewhere for cutting to desiredlength or a replacement part of proper length obtained. This problem hasbeen severe, for ex ample, in the case of cyclone separators whichnormally have an abrasive particle discharge outlet end formed as afrustum of a cone so that the length thereof determines the diameter ofthe outlet in the end. When, as in many cases, it is desirable to cutoff part of the outlet to enlarge the opening, if the outlet is formedof hard ceramic material, the above-mentioned cutting problem has beenencountered. To avoid it, it has been common practice for themanufacturer to provide cyclones initially with temporary frustoconicaloutlet ends formed of a relatively soft, nonwear-resistant but easilycut plastic. These plastic ends, made long enough to provide a minimumdiameter outlet opening, are cut at the installation site to a lengthcorresponding to the size of outlet determined by cut and try method forbest performance, thenan order is placed with the manufacturer forreplacement with a body formed of ceramic material ofthe correct lengthand outlet size.

The principal object of this invention is to obviate the problemdiscussed above by providing tubular bodies of hard ceramic material soconstructed that they may be readily severed at the installation site toadjust the length thereof as desired. A special object is to providesuch a body so constructed as a frustoconical outlet end ofa cyclone.

In accordance with the invention the tubular body of. hard ceramicmaterial is provided externally with a plurality of grooves surroundingthe axis of the body and extending partially through the wall thereof,preferably terminating in a V- shaped end or an end curved concavely ona small radius, so that the groove is deepest approximately at itscenterline. I have found that if a breaking tool such as a chisel'havingan end of a size to fit within such a groove with a wedging action onthe sides thereof is so positioned and hammered, the material severscleanly at the base of the groove entirely around its axis so that theportion of the body beyond the groove is removed, even though thethickness of the material below the groove is ample, such as about 3/16inch, to withstand breakage under use conditions and under the strainsimposed by such severing at any other groove. This surprising resultwith a material of such great hardness (e.g., harder than stainlesssteel) is apparently due to its peculiar contrasting properties of highresistance to compression, which may be of the order of 300,000 p.s.i.,but relatively low resistance to tension, its tensile strength being ofthe order of only one-tenth or less of its compressive strength. Thusthe pressure of a hammered chisel on the sides of a groove actuallypulls apart the material at the base thereof by the tension inducedthere without distorting the lands at the sides of the groovesuffciently to cause rupture of the material elsewhere even at othergrooves.

The grooves are preferably narrow, such as of the order of 1/16 inch inwidth. They are spaced apart to provide the desired frequency of groovesfor adjustment purposes which may be of the order of /z-inch spacing.The ceramic material is usually formed to a wall thickness of about to/2 inch and with such thickness I have found that grooves extendinghalfway through the wall work satisfactorily. Straight-sided grooves arepreferred except at their inner ends which are desirably V-shaped orconcavely curved on a small radius. A groove width of about 1/16 to /ainch is suitable but not critical, the function of this dimension beingto receive the point of an ordinary chisel until the chisel wedgesagainst the sides of the groove. Due to the great difficulty of cuttinggrooves in the hardened ceramic material it is preferred to form them inthe material while it is on the mold before it is heat hardened.

The invention will be further described in connection with theaccompanying drawing wherein:

FIG. 1 is a view in transverse section ofa tubular body embodying theinvention attached as a discharge passage to abrasive materialprocessing equipment partially indicated;

FIG. 2 is a view partly in elevation and partly in longitudinal sectionshowing a cyclone separator embodying the invention.

Referring to FIG. 1, a tubular body designated generally 10 has its wallformed of hard ceramic material. Body 10 as shown in frustoconical,terminating in an outlet opening 1'4 at its smaller end and having atits larger end an annular flange 16 extending outwardly with alongitudinal projection 18 on its outer part. Projection 18 forms arecess in which is seated the annular end 20 of tube partially shown at22. Tube 22'is provided with an annular flange 24 through which extendbolts 26 fastened to a ring 28 engaged under rim 16 to clamp body 10 totube 22. The passage in body l0-thus forms a continuation of the passagein tube 22 and these passages collectively may provide an outlet forabrasive material from processing equipment therefor, such, for example,as a cyclone or a feed hopper or tank containing abrasive material.

In accordance with the invention the hard ceramic wall 12 is providedexteriorly with a series of annular grooves 30 extending partly throughwall 12 and providing between them lands 32. Grooves 30 are shownV-shaped at their base and other wise are straight-sided. Theirdimensions may be as set forth above and are such that the beveled edgeof a breaking tool such as a chisel may be inserted therein to wedgebetween the sides and, when hammered, to cause the wall 12 to pull apartunder the induced tension at the base of the particular groove selectedso that the wall portion beyond the groove is removed without disturbingthe remainder of the wall.

Where the passage through body 10 is tapered'as shown, breaking off thebody opposite a groove not only shortens the body by the distance of thegroove from the original outlet, but also enlarges the outlet by anamount determined by that distance and the cone angle or angle of taperof the passage. By providing a plurality of grooves and minimum sizeoriginal outlet opening it becomes possible, by breaking off atsuccessive grooves, to determine experimentally and provide in situ thecorrect larger size outlet opening needed to suit operatingrequirements.

In cases where adjustment in length only and not in end opening size isdesirable, for example, in making connections to other equipment, thepassage through body 10 will be of uniform size throughout rather thantapered as shown. A circular cross section for the body is not essentialand it may have various polygonal shapes. It is important, however, thateach groove be separated from every other groove and surround the axisof the body completely or essentially so since any substantialinterruption of a groove is likely to prevent proper functioning, thecenter of the groove lying substantially in a single plane intersectingthe body axis.

FIG. 2 shows a hydrocyclone of a common type provided with the inventionto enable increase in size of the apex outlet as may be required to suitparticular operating conditions. The hydrocyclone has a tubular bodyformed of a cylindrical section 40 and a convergent section 42terminating in an outlet opening 44. An inlet 46 at the end of section40 supplies a slurry containing abrasive particles to be separated. Theslurry spirals about the wall of sections 40 and 42 forming an outervortex in which a fraction containing abrasive particles separatestoward the wall and is discharged from outlet opening 44. As the outervortex nears the outlet end of the convergent section an inner vortexforms proceeding in reverse direction toward the inlet end near which itpasses into the open end of a vortex finder 48, which extends throughthe end of section 40 and discharges the slurry fraction forming theinner vortex from the unit Body sections 40, 42 are formed of hardceramic material and the wall of section 42 at the outlet end thereof isprovided externally with a series of grooves 50 like and, with the samefunctional utility as grooves 30 of the FIG. 1 embodiment.

While it is common to make hydrocyclone bodies entirely of hard ceramicmaterial, it is also common to make make them of metal except in theregion of the outlet from the convergent section which is made of theharder ceramic material. In such case, the invention may take the formofa tubular member of the hard ceramic material, grooved and attached tothe remainder of the hydrocyclone body as shown in FIG. 1.

I claim:

1. A hydrocyclone separator comprising a tubular member having an inletadjacent one end, an outlet adjacent said inlet and a tubular body offrustoconical shape at the opposite end of said tubular member defininganother outlet, said tubular body being formed of abrasive-resistanthard ceramic material having a hardness of the order of 75 to 81measured on a Rockwell 45 N'scale and having a compressive strength atleast 10 times its tensile strength, said body having therein aplurality of external grooves, each said groove extending partiallythrough the wall of said body and essentially completely around the axisthereofwith its centerline lying substantially in a single plane, eachsaid groove being dimensioned to receive therein with a wedging actionagainst the sides thereof the end of a breaking tool, the tensilestrength of said material being sufficiently low so that when such toolis inserted in a groove and hammered, said body pulls apart at the baseof said groove under thetension there induced by the pressure of thetool sides on the groove walls.

1. A hydrocyclone separator comprising a tubular member having an inletadjacent one end, an outlet adjacent said inlet and a tubular body offrustoconical shape at the opposite end of said tubular member defininganother outlet, said tubular body being formed of abrasive-resistanthard ceramic material having a hardness of the order of 75 to 81measured on a Rockwell 45 N scale and having a compressive strength atleast 10 times its tensile strength, said body having therein aplurality of external grooves, each said groove extending partiallythrough the wall Of said body and essentially completely around the axisthereof with its centerline lying substantially in a single plane, eachsaid groove being dimensioned to receive therein with a wedging actionagainst the sides thereof the end of a breaking tool, the tensilestrength of said material being sufficiently low so that when such toolis inserted in a groove and hammered, said body pulls apart at the baseof said groove under the tension there induced by the pressure of thetool sides on the groove walls.